James Webb Space Telescope Prepares for Launch

Technicians at Goddard Space Flight Center in Greenbelt, Md., position the massive James Webb Space Telescope for tests in its assembly room earlier this year, in preparation for a 2018 launch. While Webb will be the most powerful space telescope ever built, astronomers are already designing its successor. The High Definition Space Telescope will have a mirror nearly twice the diameter of Webb’s 21.3-foot gold mirror and should be powerful enough to detect evidence of life on alien planets.